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Attic Insulation R-Value
At Green Attic in Chicago, we understand that achieving the right attic insulation R-value is key to maximizing energy efficiency, comfort, and long-term home performance.
Trusted by homeowners for reliable, energy-saving insulation solutions.
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Getting the Most R-Value for Your Home
Batt. Blanket. Loose Fill. Foam.
Fiberglass. Rock. Wool. Cellulose. Vermiculite. Polyurethane.
Highest R-Value Per Dollar
Testing Existing R-Value
Does your existing insulation meet current standards? More Importantly does if function as intended? Performance is measured in R-Value. R-Value is a scale of heat retention. Often Insulation is improperly installed, leaving gaps and cracks for air to travel through. Lastly, air quality is an important test.
✕ Below Current Standards
✕ Moisture problems
✕ Missing Insulation
✕ Moisture problems
✕ Missing Insulation
✕ Wet Insulation
✕ Compressed Insulation
✕ Un-insulated Exhaust Ducts
✕ Compressed Insulation
✕ Un-insulated Exhaust Ducts
R-value tells us how well insulation can resist heat flow
R= Resistance to heat escape.
• Attics is R-49/60
• Sidewalls R-21
• Cantilevered Floors R-38
• Transition Walls R-21
• Basement Walls R-13
• Crawlspace Walls R-21
Illinois current standards are moving closer to a 4.0 Air Exchange Rate and R-values consistent with optimal standards.
• Attics is R-49/60
• Sidewalls R-21
• Cantilevered Floors R-38
• Transition Walls R-21
• Basement Walls R-13
• Crawlspace Walls R-21
Illinois current standards are moving closer to a 4.0 Air Exchange Rate and R-values consistent with optimal standards.
Cost difference vs r-value difference
What is the difference in cost of different insulation materials to achieve same R-Value?
✕ Fiberglass R-Value 2.9-4.2 per inch
✕ Mineral Wool R-Value 3.0-3.2 per inch
✕ Urea formaldehyde foam insulation 5.0 per inch
✕ Plastic Board R-Value 3.7-6.0 per inch
✕ Sprayed foam R-Value 3.0-7.0 per inch
✕ Vermiculite R-Value 2.1-2.5 per inch
✕ Fiberglass R-Value 2.9-4.2 per inch
✕ Mineral Wool R-Value 3.0-3.2 per inch
✕ Urea formaldehyde foam insulation 5.0 per inch
✕ Plastic Board R-Value 3.7-6.0 per inch
✕ Sprayed foam R-Value 3.0-7.0 per inch
✕ Vermiculite R-Value 2.1-2.5 per inch
Illinois current standards for construction. Choosing the right materials.
From mineral wool to radiant barriers, spray foam insulation, fiberglass insulation, foam board insulation, blown in cellulose insulation or some other less common form such as sheep’s wool, denim or others, each is measured in terms of its R-Value.
In Chicago, current standards are measured in R-Value ( the resistance to heat escape ) measured on a scale from 0-70 for all intended purposes of this example.
✓ Attics is R49-60
✓ Sidewalls R21
✓ Cantilevered Floors R38
✓ Transition Walls R21
✓ Basement Walls R13
✓ Crawlspace Walls R21
In Chicago, current standards are measured in R-Value ( the resistance to heat escape ) measured on a scale from 0-70 for all intended purposes of this example.
✓ Attics is R49-60
✓ Sidewalls R21
✓ Cantilevered Floors R38
✓ Transition Walls R21
✓ Basement Walls R13
✓ Crawlspace Walls R21
Frequently Asked Question
What is a good R-value for attic insulation?
A good R-value for attic insulation is typically R-38 to R-60, which helps deliver strong energy savings and year-round comfort. In colder regions (Zones 5–8), R-49 to R-60 is a great target for maximum comfort and efficiency, and in warmer regions (Zones 1–4), R-30 to R-49 is typically more than enough to keep your home comfortable while saving energy. As a rule of thumb, meeting R-38 or better is a strong benchmark for noticeable energy savings.
Will more attic insulation help with cooling?
Yes, adding more attic insulation can absolutely help with cooling your home in the summer. It works like a thermal shield, blocking roof and attic heat from drifting into your living spaces, which can ease hot upstairs rooms and even cut cooling costs by around 15%–25%. With better insulation, your AC runs less often, improving comfort while reducing wear on your HVAC system.
Will I pass inspection or qualify for rebates if my insulation doesn’t meet current R-value thresholds?
Whether you pass inspection or qualify for rebates if your insulation does not meet current R-value thresholds depends on the situation, but there’s a good chance you still can, especially for existing-home upgrades. New construction or major renovations are easiest to pass when they meet today’s code minimums, and inspectors love seeing that clear match to the approved plans.
For retrofits, you’ll often have more flexibility, and you can absolutely succeed by meeting the local requirements for the specific area you’re upgrading and making sure the insulation is installed cleanly with full, even coverage.
For rebates, many programs look for a meaningful improvement, such as upgrading from R-19 or lower to R-38 or R-49, so checking your utility’s rules and documenting the before-and-after can really set you up for success.
For retrofits, you’ll often have more flexibility, and you can absolutely succeed by meeting the local requirements for the specific area you’re upgrading and making sure the insulation is installed cleanly with full, even coverage.
For rebates, many programs look for a meaningful improvement, such as upgrading from R-19 or lower to R-38 or R-49, so checking your utility’s rules and documenting the before-and-after can really set you up for success.
Will upgrading to a higher-R-value insulation reduce my energy costs significantly?
Yes, upgrading to a higher-R-value insulation can significantly reduce your energy costs, often reducing heating and cooling costs by up to 20% by slowing heat transfer.
Along with better savings, you’ll typically feel a more comfortable, even indoor temperature and put less strain on your HVAC system with higher-R-value insulation.
For the biggest impact, pair the upgrade with good installation and air sealing. Many homeowners see the investment pay back within a few years through lower monthly utility costs.
Along with better savings, you’ll typically feel a more comfortable, even indoor temperature and put less strain on your HVAC system with higher-R-value insulation.
For the biggest impact, pair the upgrade with good installation and air sealing. Many homeowners see the investment pay back within a few years through lower monthly utility costs.
Is insufficient R-value contributing to attic heat loss?
Yes, insufficient attic R-value is a major contributor to heat loss, and improving it is a great opportunity to cut energy waste by 25% or more while making your home feel warmer and more comfortable.
When insulation is too low (many older attics are around R-19 or lower), warmth can escape through the ceiling more easily, which may increase heating bills and cause uneven room temperatures or even ice dams, but upgrading insulation helps keep your home warmer, more comfortable, and more efficient.
Boosting your attic to about R-38 to R-60 and pairing it with air sealing is a great way to lock in heat, improve comfort, and reduce energy costs.
When insulation is too low (many older attics are around R-19 or lower), warmth can escape through the ceiling more easily, which may increase heating bills and cause uneven room temperatures or even ice dams, but upgrading insulation helps keep your home warmer, more comfortable, and more efficient.
Boosting your attic to about R-38 to R-60 and pairing it with air sealing is a great way to lock in heat, improve comfort, and reduce energy costs.
Should I prioritize R-value improvements if I’m planning to finish my attic, upgrade HVAC, or replace siding?
Yes, you should prioritize R-value improvements, such as insulation and air sealing, if you plan to finish your attic, upgrade your HVAC, or replace siding because it’s one of the easiest ways to boost comfort and efficiency right away.
Upgrading the building envelope first delivers fast comfort gains and can produce a strong 20% to 30% return on investment.
A tighter, better-insulated home also lets you install a smaller, more cost-effective HVAC system and enjoy immediate energy savings. If you’re finishing the attic, insulate before closing up walls, and if you’re replacing siding, it’s the perfect time to add wall insulation for an extra efficiency boost.
Upgrading the building envelope first delivers fast comfort gains and can produce a strong 20% to 30% return on investment.
A tighter, better-insulated home also lets you install a smaller, more cost-effective HVAC system and enjoy immediate energy savings. If you’re finishing the attic, insulate before closing up walls, and if you’re replacing siding, it’s the perfect time to add wall insulation for an extra efficiency boost.
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